Magnetic filter



NOV. 28, 19 67 SKOYLES ET AL 3,355,024

MAGNETIC FILTER Filed Jan. 18, 1965 INVENTORJ DEREK R. SKOYLES ARTHUR.1. TYRRELL AGENT United States Patent 3,355,024 MAGNETIC FILTER DerekRobert Skoyles, East Grinstead, and Arthur James Tyrrell, Ashtead',England, assignors to North American Philips Company, Inc., New York,N.Y., a corporation of Delaware Filed Jan. 18, 1965, Ser. No. 426,137Claims priority, application Great Britain, Feb. 3, 1964, 4,460/ 64 2Claims. (Cl. 210-222) ABSTRACT OF THE DISCLOSURE A magnetic filterhaving a stack of ring magnets between a stack of annular magnets, andclamped together. The outer diameter of the discs is greater than theouter diameter of the rings. The magnets are magnetized axially andarranged so that discs alternate with rings and the adjacent discs formpole pieces of opposite polarity.

The present invention relates to a magnetic filter for filteringferromagnetic particles from a fluid, for example oil circulating in aninternal combustion engine.

In some modern motorcars the transmission oil is combined with theengine oil and there is consequently a need for a magnetic filter whichis small and which may be inserted in the oil suction line withoutleading to a significant pressure drop. It is essential that the filtershould be efficient when the oil flows is fast at maximum engine speedssince otherwise the flow of oil may cause cavitation. The filter must beefiicient at maximum flow to hold trapped ferromagnetic material againstthe flow of oil,

An object of the present invention is to provide an improved magneticfilter. According to the present invention a magnetic filter forremoving ferromagnetic particles from a fluid comprises a plurality ofspaced annular discs of soft ferromagnetic material, rings of permanentmagnetic material interposed between the discs, and means for axiallyclamping the discs and the rings together, wherein the discs and therings are arranged to be substantially concentrical withone anotherwherein the outer diameter of the rings is smaller than the outerdiameter of the discs, and wherein the rings are magnetized axially indirections such that adjacent discs form magnetic poles of oppositepolarity. Preferably the inner diameter of the rings is larger than theinner diameter of the discs.

The discs of soft ferromagnetic material may be provided with lugs whichlocate the discs and the rings of permanent magnetic material concentricwith one another. Alternatively the discs and permanent magnets may beheld concentric with one another by means of non-magnetic bolts whichpass through apertures in the discs and which bear against the sides ofthe magnetic rings.

Suitably the permanent magnets may be made of a ferrite material, forexample that sold under the trade name Magnadur.

In order that the invention may be readily carried into effect twoembodiments thereof will now be described by way of example withreference to the accompanying diagrammatic drawings in which:

FIGURE 1 is a sectional view of a first embodiment,

FIGURE 2 is a view along the line H-II of FIG- URE 1,

Patented Nov. 28, 1967 FIGURE 3 is a sectional view of a and FIGURE 4 isa view along the line IV-IV of FIG- URE 3.

Referring now to FIGURES 1 and 2, a magnetic filter is located within ahousing 1, preferably of non-magnetic material, by any suitable means,not shown. The filter comprises a number of apertured soft ferromagneticdiscs 2 spaced apart by rings 3 of permanent magnetic material. Therings 3 are magnetized parallel to their axes in an alternating manneras indicated by the arrows 4. The ends of discs 2 are shaped as shown inFIGURE 2 so that a bolt 5, preferably of non-magnetic material, mayserve to clamp the whole assembly together. The discs 2 are providedwith lugs 6 which are bent over the rings 3 and which serve to maintainthe discs and the rings in a substantially concentric arrangement.

When a fluid passes through the filter it is divided into two streams,one down the center of the discs and the rings and the other around thediscs and the rings. The discs 2 act as pole pieces and magnetic fieldsare produced between adjacent rings, Ferromagnetic particles in thefluid are captured by these magnetic fields and become trapped in thegaps between adjacent rings 2.

The operation of the magnetic filter shown in FIG- second embodiment,

URES 3 and 4 is similar to that of the filter described with referenceto FIGURES 1 and 2. In FIGURES 3 and 4 corresponding reference numeralshave been used for parts corresponding to those shown in FIGURES 1 and2. In this embodiment however the discs 2 and the rings 3 are locatedsubstantially concentric with one another by means of bolts 7,preferably of non-magnetic material, which also serve to clamp thearrangement longitudinally. Alternatively, rods or rivets may be usedinstead of the bolts 7.

If the filter is provided with rings and discs having equal internaldiameters, a hollow sleeve, preferably of nonmagnetic material such asaluminum, may be inserted through the central bore, the ends of thesleeve being turned over to clamp the assembly longitudinally. Theassembly may then be secured in the housing by means of a bolt passingthrough the sleeve and screwed into a suitable point on the housing.With this arrangement, the fluid will only flow along the outside of therings and discs and not along the inside.

What is claimed is:

1. A magnetic filter for filtering ferromagnetic material from a flowingliquid comprising a plurality of spaced annular discs of softferromagnetic material, a plurality of rings of permanent magneticmaterial, each ring being interposed between spaced adjacent annulardiscs to form a stack, and means for axially clamping said discs andrings together, the outer diameter of each of said rings being smallerthan the outer diameter of each of said discs, and wherein said ringsmagnetize said discs axially in directions such that each disc is of amagnetic polarity opposite the adjacent disc, each of the discs in saidstack being provided with lugs projecting in opposite directions tothereby clamp said rings on either side thereof and serve to maintainthe discs and rings in a substantially concentric stacked arrangement,and whereby a flow path is formed down the center of said stack andaround said stack.

2. A magnetic filter as claimed in claim 1 wherein the end discs of saidstack are each provided With a collar, and a non-magnetic bolt adaptedto pass through said collars and to clamp said discs and rings together.

References Cited UNITED STATES PATENTS 4;, 2,705,563 4/1955 Ide 2102232,772,778 12/1956 Furey 210-222 3,062,376 11/1962 Davis 210-222 FOREIGNPATENTS 765,495 1/1957 Great Britain.

REUBEN FRIEDMAN, Primary Examiner.

F. MEDLEY, Assistant Examiner.

1. A MAGNETIC FILTER FOR FILTERING FERROMAGNETIC MATERIAL FROM A FLOWINGLIQUID COMPRISING A PLURALITY OF SPACED ANNULAR DISCS OF SOFTFERROMAGNETIC MATERIAL, A PLURALITY OF RINGS OF PERMANENT MAGNETICMATERIAL, EACH RING BEING INTERPOSED BETWEEN SPACED ADJACENT ANNULARDISCS TO FORM A STACK, AND MEANS FOR AXIALLY CLAMPING SAID DISCS ANDRINGS TOGETHER, THE OUTER DIAMETER OF EACH OF SAID RINGS BEING SMALLERTHAN THE OUTER DIAMETER OF EACH OF SAID DISCS, AND WHEREIN SAID RINGSMAGNETIZE SAID DISCS AXIALLY IN DIRECTIONS SUCH THAT EACH DISC IS OF AMAGNETIC POLARITY OPPOSITE THE ADJACENT DISC, EACH OF THE DISCS IN SAIDSTACK BEING PROVIDED WITH LUGS PROJECTING IN OPPOSITE DIRECTIONS TOTHEREBY CLAMP SAID RINGS ON EITHER SIDE THEREOF AND SERVE TO MAINTAINTHE DISCS AND RINGS IN A SUBSTANTIALLY CONCENTRIC STACKED ARRANGEMENT,AND WHEREBY A FLOW PATH IS FORMED DOWN THE CENTER OF SAID STACK ANDAROUND SAID STACK.